Stability landscape of the Atlantic overturning circulation across the climate model hierarchy
The Atlantic Meridional Overturning Circulation (AMOC) is thought to be multistable: alternative stable flow patterns may coexist with today’s vigorous overturning circulation, shaping global climate. Originally derived from a simple conceptual model, AMOC multistability has now been demonstrated across the model hierarchy, even at eddy-rich resolution. The existence of a stable weak or collapsed circulation state is thus a robust feature when adding model complexity, and can be physically explained via the salt-advection feedback. Yet, AMOC stability is often probed with respect to idealized freshwater forcing, and less is known about how the stability properties depend on changes in radiative forcing. In this talk, we explore the stability landscape of the AMOC as a function of atmospheric CO2 concentration. Using an intermediate-complexity climate model, we compute not only the stable equilibria but also the unstable edge state in between, for snapshots of pre-industrial to possible future forcing conditions. This enables a global stability view that helps make sense of the chaotic dynamics and limited predictability observed under transient climate change, i.e. future emission scenarios. We compare these results with the rate-dependent AMOC behavior found in the Community Earth System Model (CESM), guided by conceptual models that capture key ingredients of the complex models.
Date
18.03.2026
Time
13:30 h
Place
- Bundesstr. 53, room 022/023
- Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg
Organizers
- Romain Fiévet